Classical Physics and Hamiltonian Quantum Mechanics as Relics of the Big Bang (2103.08574v1)

Abstract: In a fundamental formulation of the quantum mechanics of a closed system such as the universe as a whole, three forms of information are needed to make predictions for the probabilities of alternative time histories of the closed system . These are the action functional of the elementary particles, the quantum istate of the universe, and the description of our specific history. We discuss the origin of the "quasiclassical realm" of familiar experience and Hamiltonian quantum mechanics with its preferred time in such a formulation of quantum cosmology. It is argued that these features of the universe are not general properties of quantum theory, but rather approximate features that are emergent after the Planck time as a consequence of theories of the closed system's quantum state and dynamics.